Cycles smoke not responding to wind
Wind Falloff

The force field in the scene is being affected by a high dampening due to the simulation of gravity introduced by the Falloff settings you are using. The wind is now acting as if it was dragged down by a strong force that is currently erasing its influence on the smoke.



If it is suitable for your project, my suggestion would be to simply come back to the default value of Falloff Power = 0.